Danbury State's Attorney Stephen Sedensky III had ordered Newtown police to withhold the recordings, saying they were part of an ongoing criminal investigation. But the commission found that was not enough to restrict the recordings.

"We will appeal," Sedensky told the Hartford Courantas he left the hearing room after the ruling. The recordings will not be made public during the appeal to the state Superior Court.

Commission Chairman Owen Eagan said prosecutors failed to establish that the calls would be used in a prospective law-enforcement action and that their release would damage that action, according to the Courant.

Eagan noted that neither Sedensky nor Newtown police officials listened to the 911 calls before arguing that they were exempt from disclosure.

"You made general statements, but you never even reviewed the tapes," he said.

Sedensky reportedly argued that listening to the recordings "isn't something that needed to be done" for him to conclude their release would prejudice the investigation.

Newtown resident Adam Lanza killed 26 people, including 20 children, at the school before killing himself. Earlier in the day he had shot and killed his mother, Nancy, at their home.

The Associated Press requested the 911 recordings as well as records related to police activity at the Lanza home on the day of the shootings.